Accounts from the same domain are treated as they belong to different companies

A long time ago I noticed that mail accounts from the same domain are treated as they belong to differents companies (unless they are a popular domain like @gmail or @Yahoo. com). Each group member receives list of group contacts other people what can bring to privacy violation. Could you please help me and share your view on this? Is it already fixed at ZOOm side? Thanks in advance for feedback.